1. Field of the Invention
The present invention relates to a compact device for containing and storing a plurality of chemicals and, more particularly to a device for containing such chemicals partitioned from one another, while in addition providing a means for conveniently mixing such chemicals into a composition for use.
2. Description of the Prior Art
Dental amalgams are commonly used to fill cavities drilled in teeth. An amalgam is formed by mixing a powdered or pelletized alloy with a small quantity of liquid mercury. The alloy is usually composed of a precious metal such as silver or gold combined with copper, zinc and tin. When the alloy and mercury are mixed they initially form a pliable amalgam that may be introduced into the cavity of the tooth where the dentist has drilled to remove decayed material. Once deposited in the cavity, the amalgam hardens very quickly to form a hard durable filling.
Others have provided the mercury and alloy in predetermined quantities housed in capsule form to provide a typical dosage of amalgam. The predetermined quantities of alloy and mercury must be separated so that premature mixing does not occur and the amalgam prematurely hardened. As such, the capsule is usually formed by a mixing chamber containing the alloy therein, and a second chamber containing the mercury, the two chambers separated by a partition or separating wall. When it is desired to mix the amalgam, the separating wall is removed or otherwise penetrated to allow the mercury to enter the mixing chamber. The capsule is then mechanically or manually shaken to mix the amalgam in the mixing chamber. The capsule may be opened to access the amalgam for subsequent application into the cavity of the tooth.
One particular mixing capsule is disclosed in U.S. Pat. No. 3,841,467. This capsule includes a cylindrical container closed at its bottom end and open on its opposite end for receipt of alloy powder therein. A circular plug is configured to rest on the circular upper edge of the container and has a central opening therethrough. A sealed plastic pouch filled with mercury is placed between the upper surface of the plug and the inner top surface of a cylindrical hollow cap which is in close fit sliding engagement with the outer surface of the cylindrical container. Upon pressing the cap telescopically in an axial direction over the container and relative to the plug, the pouch is compressed between the cap and the plug with enough force to rupture the pouch to flow mercury through the central opening and into the container for mixing with the alloy contained in the container. Although the capsule of this construction may have proven effective in use, the close fit slidable engagement between the cap and the container may not provide sufficient positive engagement therebetween to ensure that during shipment and storage the cap is not axially shifted or accidentally pressed downwardly upon the container to rupture the pouch causing premature mixing of the amalgam.
Others have provided threaded caps that may be threadedly engaged to the container for providing sufficient positive engagement therebetween to prevent accidental shifting of the cap relative to the container. Such threaded type of connection requires the clinician to rotate the cap a number of turns to provide sufficient axial displacement of the cap relative to the container to rupture the pouch, and also requires the clinician, once the amalgam has been mixed, to threadedly disengage the cap from the container to access the mixed amalgam contained therein. Although threaded connections may be utilized, it has been found desirable to provide a means for more easily and quickly displace the cap relative to the container for mixing, and then to more easily and quickly remove the cap from such container to access the mixed amalgam.
In addition, mixing capsules of the type described above do not typically provide any indicator for indicating when the cap has been either intentionally or accidentally shifted to cause the pouch to be ruptured.
Hence, those skilled in the art have recognized the need for a compact device to contain and store the components of a dental amalgam in a separated configuration therein and for conveniently mixing such components when desired to formulate an amalgam. It has been found desirable that such a mixing capsule facilitate quick and easy operation to combine such amalgam components for ease in mixing, and facilitate ease in accessing such amalgam once mixed. In addition, such a device should provide an indicator that allows the clinician to visualize whether or not the device is in an operative position for mixing the amalgam. Furthermore, it is desirable that such device incorporate a minimum number of relatively inexpensive components and be of a construction to facilitate ease of assembly. The present invention meets these needs and others.